Pharmacology in pregnancy and breastfeeding Flashcards
(31 cards)
What percent of women will use prescribed meds and also OTC meds during pregnancy?
60%
90%
Why may a woman be on medicines during pregnancy, childbirth and lactation?- what conditions? (6)
Hypertension Asthma Migraines Epilepsy Mental health disorders - chronic therapy long-term anticoagulant therapy use - AF
Physiological changes and drug toxicity - what are the 4 basic kinetic processes?
absorption
distribution
metabolism and elimination
excretion
How does absorption change? - oral route (2)
May be more difficult “morning sickness” nausea/vomiting - often first 3 months
Decrease in gastric emptying and gut motility
This is unlikely to be a problem with regular dosing, but may affect single doses
How does absorption change? - IM route
Blood flow may be increased, so absorption may also increase using this route
How does absorption change? - inhalation
Increased cardiac output and decreased tidal volume may cause increased absorption of inhaled drugs
Distribution changes - what will an increase in plasma volume and fat do to drug distribution?
Increase Vd
A greater dilution of plasma will?
decrease relative amount of plasma proteins.
- increase the fraction of free drug
free drug is?
pharmodyamically active
Metabolism changes - what can Oestrogen and progestogens do?
induce or inhibit liver P450 enzymes, increasing or reducing metabolism.
Phenytoin levels in pregnancy?
reduced (due to induction of metabolism)
Theophylline levels in pregnancy?
increased (due to inhibition of metabolism)
How is GFR affected with excretion changes?
GFR is increased in pregnancy by 50% leading to increased excretion of many drugs - reduction in circulating drug level
What can Excretion reduce?
plasma concentration, and can necessitate an increase in dose of medicines cleared by the kidney.
Pharmacodynamic means
pharmokinetic means?
what the drug does to the body
what the body does to the drug
Pharmacodynamic changes may affect what?
- what sites can be affected
site of drug action & the receptor response to drugs
- Concentration of drug, metabolites at sites of biological action (changes in blood flow)
Mechanism of action (changes in receptors
What may be different in pregnancy?
Efficacy
- adverse effects may be different
What factors affect placental drug transfer and drug effects on the fetus? (6)
- Drug physiochemical properties
- Rate at which drug crosses placenta and amount reaching the fetus
- Duration of drug exposure
- Distribution in different fetal tissues
- Stage of placental and fetal development
- Effects of drugs when used in combination
Placental Transfer depends on? (3)
- Molecular weight (smaller sizes will cross more easily)
- Polarity (unionised molecules cross more readily)
- Lipid solubility (lipid soluble drugs will cross the centre more easily)
What can the placenta do?
metabolise some drugs
Safest to assume all drugs will cross placenta
What type of drug crosses the placenta more easily?
Non-ionized drugs cross the placenta more easily than ionized drugs
can protein-bound drugs cross the placenta?
yes, for non-bound versions this is not true
Lipophilicity affect on placental transfer?
transfer
Fetal pharmacokinetics - Distribution - why is this different compared to an adult (4)
Circulation is different (e.g. Umbilical vein to liver)
Less protein binding than adults therefore more “free” drug available
Little fat, so distribution different
Relatively more blood flow to brain , less well developed blood brain barrier
